Plane astronomy |
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Page 10
... described agree with the supposition of the Earth's being a sphere ; and , indeed , no other hypothesis would account for them , since a sphere only would give a circular offing of the same dimensions at every part of the surface ...
... described agree with the supposition of the Earth's being a sphere ; and , indeed , no other hypothesis would account for them , since a sphere only would give a circular offing of the same dimensions at every part of the surface ...
Page 12
... described by the Earth's E E centre during one complete ro- tation on the axis . Let the line SE cut the Earth's surface in A. When the Earth has ar- rived at E , the line E'A ' , pa- rallel to EA will be , by what has preceded the ...
... described by the Earth's E E centre during one complete ro- tation on the axis . Let the line SE cut the Earth's surface in A. When the Earth has ar- rived at E , the line E'A ' , pa- rallel to EA will be , by what has preceded the ...
Page 14
... described by a point in the equator . The points P , p remain stationary , and it is evident from the figure that the former is in the enlightened hemisphere , and the latter in the unenlightened hemisphere . There is therefore ...
... described by a point in the equator . The points P , p remain stationary , and it is evident from the figure that the former is in the enlightened hemisphere , and the latter in the unenlightened hemisphere . There is therefore ...
Page 15
... described by the line SE . Hence , in the course of a revolution , the angle PKM goes through all values from 0 ° to 360 ° , and PM undergoes corresponding changes . P K " P M It is clear that the greatest value of PM is P'M , and its ...
... described by the line SE . Hence , in the course of a revolution , the angle PKM goes through all values from 0 ° to 360 ° , and PM undergoes corresponding changes . P K " P M It is clear that the greatest value of PM is P'M , and its ...
Page 21
... described but we gain a near approximation to its actual motions by supposing the orbit to be a plane circle , having the Earth in its centre , and carried round with the Earth in its annual orbit . The effect may be illustrated by sup ...
... described but we gain a near approximation to its actual motions by supposing the orbit to be a plane circle , having the Earth in its centre , and carried round with the Earth in its annual orbit . The effect may be illustrated by sup ...
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Common terms and phrases
accurately angular distance antarctic circle apparent direction appear astronomical axis azimuth bisects called celestial equator celestial sphere clock coincide conjunction consequently correction curve declination described determined diameter diurnal motion Earth Earth's centre Earth's orbit Earth's surface eclipse enlightened hemisphere equal equinox error exactly field of view fixed stars greatest heavenly bodies Hence horizon-glass inclination index-glass inferior planet instrument intersection latitude limb line of collimation line of graduation line of nodes longitude lunar lunar eclipses means measured meridian altitude Moon motion mural circle nearly object-glass observed angle opposite parallax parallel passed the meridian perigee perpendicular phenomena plane pole position radius reflected image refraction revolution revolves right angle right ascension sea-line seen sextant shadow shewn sidereal sidereal day Sidereal period solar solstice space sphere of observation spherical straight line subtended Sun's supposing Synodic period tangent telescope transit true direction velocity vernier wire zenith distance zero
Popular passages
Page 6 - A sphere is a surface every point of which is equally distant from a point within it,
Page 6 - (1). Every section of a sphere made by a plane is a circle. Let
Page 14 - between the tropic of Cancer and the arctic circle, and between the tropic of Capricorn and the antarctic circle, are called respectively the
Page 3 - varies directly as the mass of the attracting body and inversely as the square of its distance from the attracted body.
Page 23 - the altitude of the pole above the horizon is equal to the latitude of the place. The
Page 2 - planet is attracted to the sun by a force varying inversely as the square of the distance from the sun.
Page 7 - When the cutting plane passes through the centre of the sphere, the section is called a great circle.
Page 7 - The diameter of the sphere which is perpendicular to the plane of any
Page 7 - of the Earth is inclined to the plane of the orbit at an angle of about 66°
Page 69 - passes through the centre of the horizon-glass, meeting its surface at the same angle as the line drawn from the same point to the centre of the index-glass. Hence a ray of light reflected from the centre of the index-glass to that of the horizon-glass is again reflected along the line of collimation of the telescope.